[INTERNAL] sap.ui.dt: isElementVisible: first check DTMD, then geometry
[INTERNAL] sap.ui.dt: isElementVisible: first check DTMD, then geometry

priority change, first the designtime metadata isVisible function is
called, then the geometry is calculated and used

Change-Id: I400ae1cc68350aa1c64744680cff52a548036ea5
Signed-off-by: Kevin Edinger <2cd308f6e534f22a23b481bd971d726fce0a3425@sap.com>
BCP: 1980184822
SAP/openui5,SAP/openui5,SAP/openui5,SAP/openui5